Rapid diffusion of wireless devices typified by mobile communications increases the demand for small and light acoustic wave resonators and filters formed by combining them. Widely used as the acoustic wave resonators are piezoelectric thin film resonators such as Surface Acoustic Wave (SAW) resonators, Film Bulk Acoustic Resonators (FBARs), and Solidly Mounted Resonators (SMRs). There has been known a technique that divides an acoustic wave resonator to reduce second harmonic generated by the acoustic wave resonator as disclosed in, for example, Japanese Patent Application Publication Nos. 2008-85989 and 2009-10932 (hereinafter, referred to as Patent Documents 1 and 2, respectively).
When a resonator is divided so as to reduce the second harmonic as described in Patent Documents 1 and 2, the number of resonators increases, thereby increasing the chip size. In addition, because of the parasitic capacitance of a wiring line connecting the divided resonators, the degree of reduction of the second harmonic may become insufficient.